First it was existing lawns, with Gov. Jerry Brown leading the way in urging Californians to rip out swaths of green to save vast amounts of water.

Now state regulators have their sights set on grass that hasn't even been planted.

The California Water Commission is scheduled to consider new rules Wednesday that would significantly slash the amount of water that can be used by landscapes surrounding newly built houses, businesses and schools.

Experts say that the changes, which if approved could take effect by Dec. 1, could signal a significant shift in how residents envision their perfect California home.

"It will be a far more interesting place than this monoculture of grass," said Esther Margulies, an instructor in the landscape architecture program at USC. "The attraction to subdivisions with pristine lawns has changed.… People are a lot more sophisticated and urbane … [and] much more likely to let go."

Lawn space regulations

Brown's historic April 1 drought order required regulators to revise the Model Water Efficient Landscape Ordinance to increase water efficiency and limit the areas that can be covered in turf.

Under the revised ordinance, grass would be all but banned in landscapes of new commercial, industrial and institutional buildings and could consume only about 25% of a homeowner's combined front, back and sideyards.

The changes would apply to new construction with landscape areas larger than 500 square feet and also to existing landscapes larger than 2,500 square feet that undergo complex renovations. Exemptions are included for recreational areas, and landscapes irrigated with recycled water.

Officials emphasized that families can still install a small amount of lawn at their homes where children or pets can play. Even nonresidential landscapes could include a small slice of turf if the rest of the area is covered in plants that use very little water.

"This is … the entire direction the state has been going," said Peter Brostrom, water use efficiency program manager for the Department of Water Resources. "The state's view of what a typical California landscape looks like is changing.… Making sure our landscapes conform to the new reality of our water supply is very important."

Regulators have been tweaking rules on landscape water use for years.

The first version of the model ordinance was adopted in 1992, about the time another statewide drought was ending. Those regulations applied to landscapes larger than 2,500 square feet and allowed them to be covered in about 50% grass, officials said.

The ordinance was revised in 2009 to allow for about 14% less water use, but officials figured that with new, more efficient sprinkler technology, Californians could maintain the same foliage in their yards while still using less water.

Since that time, landscape architects say their clients have started questioning whether grass is the best way to cover their new landscapes. In some cases, they have asked for drought-tolerant plants in the spots where turf used to be.

Samantha Harris, a landscape architect for Rios Clementi Hale Studios in Los Angeles, said many of her company's clients are realizing that "a lot of the space taken up by lawn isn't always well used."

"We're seeing a shift, reevaluating landscape to be more usable and occupiable," she said, citing creative-office properties that use their outdoor space for meetings, classrooms or game areas. "We're going to have less reliance on lawn, which isn't a bad thing, and in its place, more active programmatic spaces that get people out of their homes. … This [ordinance] is helping that."

Critics of the new rules say the landscaping ordinance strips homeowners of their freedom to plant as they choose and accuse state regulators of leveraging the drought to kill lawns in California.

In a comment letter, Larry Rohlfes, an official at the California Landscape Contractors Assn., said his group was "concerned that the Model Ordinance may be evolving into an overly strict and complicated document that is becoming dauntingly difficult to understand, comply with, and enforce."

The water-use reduction requirements "make us nervous," he wrote. "We can't help but wonder if the drought is being used to make permanent changes in what California's landscapes will look like."

But Tracy Quinn, a policy analyst for the Natural Resources Defense Council, called the proposed water allocations for landscapes sufficient and effective.

"As more drought-tolerant native plants become available in the nurseries and home improvement stores throughout the state, we could definitely push further … so that we eliminate high-demand plants in our landscape altogether," Quinn said.

Californians have been tearing out their turf in record numbers as they strain to conserve water amid the drought. Last week, the Metropolitan Water District of Southern California announced that it had exhausted more than $300 million in turf removal rebate funds.

Heather Cooley, water program director at the Pacific Institute, said the updated regulation will help ensure that more new lawn isn't being added just as millions of square feet are being ripped out.

"This ordinance combined with the rebate and incentive programs will cause us to reimagine our urban areas," she said. "It's forcing us to prioritize our water uses, and ornamental lawns are no longer appropriate for California."